I'm having trouble following the sequence of events and temperatures, but what I do for a lager starter is mostly the same as an ale starter...smack the pack at room temp, cool the starter wort to room temp, pitch & ferment at room temp. The only difference is that after starter fermentation I gradually bring the starter down to pitching temp (usually ~50-52F) so that it will be at the same temp as my wort when I pitch.
Frequently changing the temperature of yeast and/or doing it rapidly usually doesn't make it happy.
Also, if possible, I'd suggest a 1g starter for most lagers. They require pretty large pitching rates. For me this means splitting the smack pack between two 2L growlers.